Hydrazides of benzoic acid and derivatives thereof as antioxidants for fats and oils



' rates HYDRAZIDES or BENzorcACID AND DERIVA- rrvns rrmREor AS ANTIOXIDANTS non FATS AND ons N Drawing. Application August 23, 1954,

Serial N0. 451,674

8 Claims. (Cl. 260-3985) This invention relates to the stabilization of organic materials which are subject to deterioration by the employment of one or more of a group of antioxidants, namely benzhydrazide and substituted derivatives thereof. These derivatives are believed to be novel compounds which are especially eflicacious for this purpose. This invention is more particularly directed to the stabilization of fats and fatty oils.

The antioxidants of this invention can be advantageously prepared by reacting a lower alkyl ester of benzoic acid (or nuclear substituted derivative thereof) with hydrazine hydrate or a monosubstituted derivative of hydrazine in solution in a suitable solvent such as ethanol, ether, etc. The acid chloride can be employed in lieu of the alkyl ester of benzoic acid or its derivative. Examples of such preparations are given below.

Gentisic acid hydrazide (also called gentishydrazide) is one of the most efiicacious antioxidants of this invention yet protocatechuic acid hydrazide (which is an isomer) is worthless as an antioxidant for fats and fatty oils, e. g. lard 0r castor oil. Gallic acid and its esters are useful antioxidants for fats and oils whereas gallic acid hydrazide is Worthless. Moreover, gallic acid is a better antioxidant for fats and oils than is gentisic acid; but conversely, the gentisic acid hydrazide is unusually potent and the gallic acid hydrazide is worthless. It is well recognized that many derivatives of aromatic acids such as esters and amides possess valuable antioxidant properties; moreover, the antioxidant activity is closely associated with ortho or para dihydroxy substitution with no activity ordinarily being displayed in the absence of substituents in such positions. Thus, gentisic acid, protocatechuic acid, gallic acid and 1,3,5-trihydroxybenzoic acid or their esters or amides are all effective antioxidants but benzoic acid, salicylic acid, 3,5-dihydroxybenzoic acid or their esters or amides are ineffective.

We have now found that the hydrazides of these ineffective aromatic acids are quite unexpectedly useful as antioxidants for fats, fatty oils and other organic materials which are subject to deterioration. Most unexpectedly, some of the efiective aromatic acids are rendered ineffective by the presence of the hydrazide structure, e; g. gallic acid hydrazide and protocatechuic acid hydrazide. We have found it appropriate to exclude from our new class of antioxidants those substituted derivatives of benzhydrazide which contain substituents on the aromatic nucleus which are ortho to another substituent other than the hydrazide structure.

It is an object of this invention to provide a new class of antioxidants which are especially useful for inhibiting the deterioration of fats and oils. Another object is to provide a process for employing such antioxidants to stabilize organic materials subject to deterioration such as fats and fatty oils. A further object is to provide novel compositions of matter comprising fats, fatty oils and the like which contain these antioxidants. Still another object is to provide novel chemical compounds which are I Patented Oct. 1, 1957 ice useful as antioxidants. Other objects will become apparent hereinafter.

A principal embodiment of our invention relates to a stabilized product comprising a substrate selected from the group consisting of fats and fatty oils containing from about 0.001% to about 1% by Weight of an antioxidant selected from the group consisting of benzhydrazide and compounds having the following generic formula:

wherein R1 represents a member selected from the group consisting of a hydrogen atom, an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical containing from 6 to 9 carbon atoms, and R2, R3, R4, R5, and Re representtwo nonadjacent members selected from "it: group consisting of an alkyl radical containing from 1 to 6 carbon atoms; an aryl radical containing from 6 to 9 carbon atoms, a hydroxy radical, an alkoxy radical containing from 6 to 9 carbon atoms, an amino radical, a chlorine atom, a bromine atom and an iodine atom, and the remaining three of R2, R3, R4, R5, and Re represent hydrogen atoms.

Examples of compounds coming within the scope of the generic formula include those set forth in the tables presented below and also include Z-hydroXy-S-tert. butoxybenzoic acid ethyl hydrazide, 2sec. hexylbenzoic acid isopropyl hydrazide, 2-tert. butyl-4-hydroxybenzhydrazide, 2-amino-4-(p-tolyl)-benzhydrazide, 2-chloro-5-ethylbenzhydrazide, 3-iodobenzhydrazide, 6-ethylbenzhydrazide, etc.

As indicated in the second paragraph of this specification the antioxidants of this invention can be prepared by relatively simple procedures. The following examples will serve to further illustrate how some of these compounds can be advantageously produced.

EXAMPLE l.GENTISHYDRAZIDE A solution of 46 grams (0.25 mol.) of ethyl gentisate and 15 grams (molecular excess) hydrazine hydrate dissolved in 25 ml. of ethanol was warmed on a steam bath for one hour. The resulting precipitate was collected and Washed with hot ethanol. Recrystallization from ethanol gave 32 grams (76% yield) of gentishydrazide, M. P. 216217 C., with decomposition.

Analysis. Calcd. for CvHaOsNz: C, 49.99; H, 4.79; N 16.67. Found: C, 49.96; H, 5.01; N, 16.79.

EXAMPLE 2.GENTISIC ACID PHENYL HYDRAZIDE A solution of 25.6 g. (0.1 mole) 2,5-diacetoxybenzoylchloride. in ml. of ether was added slowly to a solution of 216g. (0.2 mole) of phenylhydrazine in 250 ml. of ether. The mixture was allowed to stand for 24 hours and then filtered. The filter cake was washed with warm Water and the water-insoluble portion was dissolved in ml. of 10%aqueous sodium hydroxide solution. This solution was cooled and acidified. The resulting oil was crystallized from ethanol to give 16 g. of the desired compound, M. P. 161162.

Analysis.Calcd. for C13H1203N2Z C, 63.92; H, 4.95; N, 11.47. Found: C, 63.71; H, 5.16; N, 11.76

EXAMPLE 3.2,4-D1HYDROXY BENZ HY DRAZIDE This compound was prepared from methyl 2,4-dihydroxy benzo'ate and hydrazine hydrate in exactly the same manner as described in Example 1. The product obtained had 'a melting point of 238242 C., with decomposition.

Analysis.Calcd. for C-zI-IsOaNz: C, 49.99; H, 4.79; N, 16.67. Found: C, 49.85; H, 4.83; N, 16.70

EXAMPLE 4.--2-I-IYDROXY-5-METI-IOXYBENZHY- DRAZIDE This compound was prepared from methyl 2-hydr'oxy- S-methoxybenzoate and hydrazine hydrate in exactly the same manner as described in Example 1. This compound had a melting point of 163-4 C.

AnaZysis.Calcd. for'CsI-hoOaNz: C, 52.80; H, 5.50; N, 15.31. Found: C, 52.75; H, 5.46; N, 15.36.

EXAMPLE 5.--2-AMINOBENZOIC ACID PHENYL HYDRAZIDE This compound was prepared from methyl Z-aminobenzoate and phenylhydrazine in the manner described in Example 2.

Other compounds coming within the scope of the generic formula can be prepared following similar procedures to those described in the foregoing examples. The properties of some of these compounds are set forth in the tables presented below.

The compounds described hereinabove and covered by the generic formula together with benzhydrazide are useful as antioxidants in fats, vegetable oils, rubber, synthetic and natural resins, plastic compositions, vitamincompositions, animal and vegetable waxes, the vitamin'content of crops such as alfalfa, etc. Examples of compounds which can be stabilized and which come within thescope of these broad classes include cracked gasoline, motor oils, carnauba wax, beeswax, paraffin wax, lard, cottonseed oil, linseed oil, castor oil, cellulose acetate, polyesters, polyethylene, synthetic rubber compositions, lan-' olin, corn oil, butter, turpentine, etc.

When employed as antioxidants fractions of a percent of these compounds can be incorporated into suchsubstrate materials as have just been mentioned by admixing the antioxidant compound with the substrate whereby a solution or suspension of the antioxidant in the substrate is obtained.

Alternatively the antioxidant-can be blended with a suitable solvent to form an antioxidant solution which can then be advantageously mixed with the substrate. Examples of solvents useful in the preparation of such solutions include various alcohols, ethers, oils, and various other organic compounds in which these antioxidants are soluble. Moreover, liquids in which 'they can be suspended by appropriate means can also be employed. These concentrated solutions 'or suspensions are advantageous in preparing the stabilized material since they reduce the amount of 'mixing or blending which would otherwise be required. 'They can be quite-readily distributed uniformly through the substrate-without prolonged mixing.

When solvents are employedin the preparation of antioxidant concentrated solutions, such solvents can be present in an amount just sutficient to dissolve the antioxidant up to any larger amount which may be desired especially if larger amounts are necessary to fully dissolve other supplementary antioxidants or synergists which may be incorporated into the antioxidant "solution.

In a similar manner syn-ergists can be admixed with the fats, fatty oils or other substrate along with the antioxidant compounds of this inventionor, in order-to facilitate the incorporation of the antioxidant and synergist into the substrate they can both be dissolved in a suitable solvent which is inert insofar as concerns both the anti oxidants and/or thesynergist as well as the ultimately,

prepared and stabilized substrate. Synergists which are Well-known. in the art include various organic acids such as citric acid, ascorbic acid, etc. as well as inorganic acid suchas phosphoric acid and numerous other compounds.

In addition to thepresencerof a single antioxidant as described by our invention, a mixture of such antioxidants can be employed or one or more antioxidants of our invention can be employed in combination or other antioxidants which are known in the prior art and which can be added for their supplemental effects if such be desired, e. g. propyl gallate, tert. butylhydroxyanisole, 3,5-ditert. butyl-4-hydroxytoluene, etc.

Inasmuch as itis well known in the art to employ antioxidants in the stabilization of fats, oils, and other substrates, itis not believed'to be necessary to give numerous specific examples of how the antioxidants of this invention can be blended with the fats, oils or the like. The

A most suitable methods of blending antioxidants and syn- (BHA) and propyl gallate.

ergists in'particula'r substrates can be readily determined by those skilled in the art. The range of antioxidant proportions which can be employed is advantageously from about 0.001% up to as much as 1% or more by weight of the antioxidant in the substrate depending upon the nature of the substrate'and the effects desired. Generally a range of proportions from about 0.001% up to about 0.1% is sufficient. In fact, quantities such as 0.01% to 0.05% will usually suffice to give adequate-stabilization against deterioration. c

The following tables are presented in order to further illustrate our invention. The data presented in these tables are based on tests conducted under the same conditions employing similar samples in each instance of lard or castor oil. The procedure employed under the active oxygen method (AOM) is well known in the antioxidant art and needs no further explanation in this specification. The AOM figures are 'in hours and represent the time required. forlard to reach a peroxide content of 20 milequivalents for kilogram. In both of these tables the concentration of'the antioxidant is 0.02% based upon the weight'of the substrate. Data is presented in these tables for certain 'of the commercially available wellknown antioxidants such as tertiary butyl hydroxyanisole value of the antioxidants of this invention the data is presented in the form of an antioxidant index using BHA as the standard for-comparison. This index (A. I.) is calculated by dividing the A. O. M. value for each anti- 7 oxidant by the A. O. M. value for BHA.

BHA

Table'I.-Anti0xidant effectiveness of benzhydrazide and its derivatives in lard Antioxidant A. O. M.

None (control sample) 8.0 BHA Gentishydrazlde Gentistc acid phenyl hydrazide Salicylhydrazide Z-Aminobenzoic acid phenylhydrazide 2-Hydroxy-5-methoxybenzhydrazide p-Hydroxybenzhydrazide Protocatechuic acid hydrazide Gallic acid hydrazide i- 2L3 less than control same ascbntrol Time in Hours To Reach Antioxidant Peroxide Number of 70 meq. g. kg.

35 91 95 30 95 97 Propyl gallate 95 210 213 Gentisic acid phenylhydrazide. Gentishydrazide 205 307 312 It is clear fro'm'the above tabl'es, that gentishydrazide' is one of the most effective antioxidants of this new class For quick appraisal of the of antioxidant compounds. It was quite unexpected to discover that gentishydrazide has the highest potency of any known antioxidant for castor oil. In fact, it was quite surprising to find that all of the subject antioxidants retain high potency in oils such as castor oil since many etfective antioxidants for fats such as lard have relatively little value in fatty oils such as castor oil, this being illustrated by the data regarding BHA in castor oil.

The especially valuable antioxidants which come within the scope of this invention are gentishydrazide and the aryl and alkyl hydrazides of gentisic acid as illustrated by the phenylhydrazide in the tables. These especially valuable antioxidants are novel compounds which come within the scope of the generic formula where R1 is as defined above, R2 and R5 are hydroxyl radicals and R3, R4 and Re are hydrogen atoms.

In addition to the specific compounds which have been set forth in the above tables it is obvious that other antioxidants coming within the scope of this invention can be similarly employed, examples being those compounds which have been specifically. named hereinabove. These compounds can be employed to stabilize any of the substrates named above but are especially useful in fats and fatty oils, e. g. butter, cottonseed oil, peanut oil, suet, etc.

We claim:

1. A stabilized product comprising a substrate selected from the group consisting of fats and fatty oils containing from about 0.001% to about 1% by weight of an antioxidant selected from the group consisting of benzhydrazide and compounds having the following generic formula:

wherein R1 represents a member selected from the group consisting of a hydrogen atom, an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical containing from'6 to 9 carbon atoms, and R2, R3, R4, R5 and Rs represent two nonadjacent members selected from the group consisting of an alkyl radical containing from 1 to 6 carbon atoms, an aryl radical containing from 6 to 9 carbon atoms, a hydroxy radical, an alkoxy radical containing from 6 to 9 carbon atoms and an amino radical, and the remaining three of R2, R3, R4, R5 and Rs represent hydrogen atoms.

2. A stabilized product as defined by claim 1 wherein the antioxidant is gentishydrazide.

3. A stabilized product as defined by claim 1 wherein the antioxidant is gentisic acid phenyl hydrazide.

4. A stabilized product as defined by claim 1 wherein the antioxidant is benzhydrazide.

5. A stabilized product as defined by claim 1 wherein the antioxidant is 2,4-dihydroxybenzhydrazide.

6. A stabilized product as defined by claim 1 wherein the antioxidant is salicylhydrazide.

7. A stabilized product as defined by claim 1 which contains from about 0.0001% to about 0.1% by weight of a synergist.

8. A process for stabilizing and inhibiting the deterio: ration of fats or oils which comprises admixing a substrate selected from the group consisting of fats and fatty oils with from about 0.001% to about 0.1% by weight based on the substrate of a compound having the following generic formula:

wherein R1 represents a member selected from the group consisting of a hydrogen atom, an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical containing from 6 to 9 carbon atoms, and R2, R3, R4, R5 and Rs represent two nonadjacent members selected from the group consisting of an alkyl radical containing from 1 to 6 carbon atoms, an aryl radical containing from 6 to 9 carbon atoms, a hydroxy radical, an alkoxy radical containing from 6 to 9 carbon atoms and an amino radical, and the remaining three of R2, R3, R4, R5 and Rs represent hydrogen atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,430,031 Shappiro Nov. 4, 1947 2,463,461 Hofier Mar. 1, 1949 2,463,462 Huck Mar. 1, 1949 2,716,663 Beman Aug. 30, 1955 2,763,684 Beman Sept. 18, 1956 FOREIGN PATENTS 423,938 Great Britain of 1935 

1. A STABILIZED PRODUCT COMPRISING A SUBSTRATE SELECTED FROM THE GROUP CONSISTING OF FATS AND FATTY OILS CONTAINING FROM ABOUT 0.001@ TO ABOUT 1% BY WEIGHT OF AN ANTIOXIDANT SELECTED FROM THE GROUP CONSISTING OF BENZHYDRAZIDE AND COMPOUNDS HAVING THE FOLLOWING GENERIC FORMULA: 